Influence of surface roughness on friction properties (Part 1) - Relationship between indented depth and friction coefficient

This research deals with the influence of the surface roughness on the friction properties for a hard hemispherical projection sliding on a smooth soft surface or a soft one with the triangular prismatic projections. The sliding direction in this paper is vertical for the axis of prismatic projections arranged in parallel on the base surface. This paper is examined on the effects of various factors on the relationship between the indented depth and the friction coefficient, The friction mechanism between the hard hemispherical projection modeled on the asperity of a hard material surface and the soft surface has been theoretically analyzed taking into consideration with the frictional resistance caused by the ploughing and shearing term. The results of numerical examples based on theoretical analysis can be expressed as follows. The friction coefficient for the smooth soft surface increases with the increase of a contact angle that obtains from the radius of curvature and an indented depth of the hemispherical projection, The friction coefficient for soft surface with the asperities periodically fluctuates with the increase of an indented depth and the friction coefficient between the hard projection and the smooth soft surface has a converging tendency.